This application is the national phase under 35 U.S.C. xc2xa7371 of PCT International Application No. PCT/DE99/03240 which has an International filing date of Sep. 30, 1999, which designated the United States of America.
The invention relates to an electrical power circuit breaker. More specifically, it relates to an electrical power circuit breaker having the following features:
an electromechanical assembly having at least one switching contact, a drive apparatus which operates the switching contact and associated latching devices for allowing energy stores to close and open the switching contact,
a current sensor for detecting a current flowing via the switching contact,
an electronic overcurrent trip unit for processing a signal from the current sensor and for emitting a signal to allow the latching device to open the switching contact,
a moving connecting line for connecting the current transformer to the overcurrent trip unit, and
an information memory for passing characteristic values of the electromechanical assembly in the power circuit breaker to the overcurrent trip unit.
A power circuit breaker has been disclosed, for example, in WO 97/08725. In this case, the information memory is located on the outside of the housing of the overcurrent trip unit, and is detachably fitted thereto. Fitting the information memory to the overcurrent trip unit means that, when the overcurrent trip unit is being tested after removing it from the power circuit breaker, the information memory is also included in the test and any faults in it are also detected. This procedure assumes that, when the current transformer in the power circuit breaker is replaced, the information memory also needs to be replaced or its programming needs to be adapted. Similar measures are required with an arrangement according to EP 0493 272 B1, in which an interface card, fixed to the switch, is provided. Further, firstly the current transformer and secondly the overcurrent trip unit must be connected to the interface card.
The two different systems (WO 97/08725 A1 and EP 0 493 272 B1) do not necessarily include the current transformers (and/or current sensors) in the information chain required for correct operation of such a power circuit breaker.
In contrast to the known systems, the invention is based on the object of improving the reliability against spurious operation of the power circuit breaker, by improving the transfer of parameters to the electronic overcurrent trip unit.
According to the invention, this object is achieved based upon the fact that the information memory is a part of a first component, which is connected on the connecting line of a two-part plug and socket apparatus, whose second component is part of the overcurrent trip unit. The installation of the current transformer in the power circuit breaker or the subsequent replacement of the current transformer in this way defines the rated current of the power circuit breaker. At the same time, this information memory can be used to define further characteristic values, such as the switching rating class or the Standard class of the power circuit breaker. In this case, the term switching rating class refers to the rating of the electromechanical assembly in accordance with a specific required switching capacity, for example, which is stated in kA. The term Standard class in the present context refers to a design in accordance with specific regional regulations, for example. In particular, it refers to those for the IEC market, the ANSI market or the UL market. It should also be mentioned that, in the present context, the term characteristic value refers to a combination of a specific parameter, for example the rated current, with a value of the rated current.
Since, as is known, resistors are among the most reliable and simplest electrical components, it appears to be advantageous to form the information memory by means of resistors, for example. These resistors can expediently be connected between the contact pins of the first component of the plug apparatus. If, for example, four characteristic values need to be coded, (for example the rated current of the power circuit breaker, its physical size, the switching rating class and the Standard class) then one resistor can be provided for each of these for this purpose. The resistance can be between approximately 1xcexa9 and approximately 1 Mxcexa9, for example, with defined steps of the characteristic values being allocated to the resistance values. In this way, 16 different values can be defined, for example, without any error within said range of resistance values.
If only a limited number of characteristic values need to be stored, then, according to a further refinement of the invention, this can be achieved by providing only a single resistor, whose resistance represents a predetermined combination of characteristic values.
A plug connector for connecting a medical sensor to an electronic evaluation appliance and which contains an electronic coding element is already known (U.S. Pat. No. 5,660,567 A1). The coding element simplifies the sensor since this now does not need to contain any calibration device. The field of application of the known plug connector is a two-part arrangement (sensor and evaluation appliance), while the subject matter of the invention explained above is a three-part arrangement, including an electrical power circuit breaker, current transformers for measuring the current flowing via the current path in the electromechanical part of the power circuit breaker, and an electronic overcurrent trip unit for opening switching contents. Furthermore, it was not possible to find any idea leading to the invention explained above from the cited document, since the idea for and result of the known measure are considerably different from the invention. In particular, the known arrangement does not lead to the idea that a plug connector can be equipped with a way for coding all the characteristic values which define the interaction of the power circuit breaker (electromechanical part), current transformer and overcurrent trip unit.